Image scanners are commonly used in offices or homes for scanning for example documents, photographs or films. The scanned images can be converted into an electronic file so as to be stored in a computer or directly printed.
An image scanner principally comprises an optical scanning module and an electronic signal processing circuit. The scanning module comprises a light source, an image sensor such as a charge coupled device (CCD), a lens, and a reflective mirror. The light emitted from the light source is projected onto an object to be scanned. The light reflected from the scanned object is focused by the lens and then received by the CCD. According to the intensity of the received light, the CCD produces electronic signals of images.
As known, a precise focusing adjustment between the CCD and the lens is required during the scanning operation. If the focusing adjustment is improper, the quality of the scanned image is not satisfactory. Therefore, it is important to precisely, quickly and conveniently adjust the position of the CCD relative to the lens during the process of fabricating the scanning module.
Conventionally, in the process of fabricating a scanner with low resolution, the position of the CCD relative to the lens is manually adjusted to achieve orientation by an experienced worker in a production line. This process, however, is not applied to fabricate the scanner with high resolution.
One mechanism for adjusting the position of the CCD relative to the lens is described in Taiwanese Patent Gazette No. 407826, entitled “Adjustable fixing device of a CCD plate.” Such a mechanism can adjust the CCD plate in four degrees of freedom. In addition, Taiwanese Patent Gazette No. 407826 also discloses another mechanism for adjusting the CCD plate in five degrees of freedom.
As known from the above discussion, those skilled in the art keep on researching other mechanisms for adjusting the CCD in more degrees of freedom in order to meet the requirement of the scanner with high resolution.